Jabir b. Abdullah reported that two young men, one from the Muhajirin (emigrants) and the other one from the Angr (helpers) fell into dispute and the Muhajir called his fellow Muhajirin, and the Ansari (the helper) called the Ansar (for help). In the meanwhile, Allah's Messenger (ﷺ) came there and said
What is this, the proclamation of the days of jahiliya (ignorance)? They said: Allah's Messenger, there is nothing serious. The two young men fell into dispute and the one struck at the back of the other. Thereupon he (the Holy Prophet) said: Well, a person should help his brother whether he is an oppressor or an oppressed. If he is the oppressor he should prevent him from doing it, for that is his help; and if he is the oppressed he should be helped (against oppression).
Jabir b. Abdullah reported
We were along with Allah's Messenger (ﷺ) in an expedition that a person from amongst the emigrants struck at the back of a person from the Ansir. The Ansiri said: O Ansar! And the Muhijir said: O Emigrants! Thereupon Allah's Messenger (ﷺ) said: What are these proclamations of the Days of Ignorance? They said: Allah's Messenger, a person from the emigrants struck at the back of an Ansari, whereupon he said: It is something disgusting. 'Abdullah b. Ubayy heard it and said: They have indeed done it. By Allah, when we would return to Medina the respectable amongst them (the Ansar) would turn away the mean (the emigrants). Thereupon 'Umar said: Permit me so that I should strike the neck of this hypocrite. But he (the Holy Prophet) said: Leave him, the people may not say that Muhammad kills his companions.
Jabir b. 'Abdullah reported that a person from the emigrants struck the back of an Ansari. He came to Allah's Apostle (ﷺ) and asked for compensation. Thereupon Allah's Apostle (ﷺ) said
Leave it. for it is something disgusting. Ibn Mansur said that in the narration transmitted on the authority of Amr (these words are also found):" I heard Jabir."